Lubricating composition



Patented Apr. 12, i938 PATENT OFFlCE LUBRICATING COMPOSITION John C.Zimmer, Hillside, and Arnold J. Morway, Roselle, N. J., assignors toStandard Oil Development Company, a corporation of Dela- No Drawing.Application June 6, 1935, Serial No. 25,308

7 Claims.

The present invention relates to improvements in oils and specificallyto improvements in the lubricating properties of oils and greases. Theinvention will be fully understood from the following description of thecomposition and the methods of manufacturing same.

Hydrocarbon lubricants are not characterized by an exceptionally highdegree of oiliness, and in recent years it has been found desirable tofind methods for increasing the oiliness or lubricity of thesematerials. Various substances have been added to the oils, such as fattyacids, their esters, chlorinated materials and the like; but most ofsuch materials are undesirable in one I r or more respects-although theymay produce a marked improvement in one or more differentcharacteristics. There has been a steady search for materials whichwould improve the oiliness without increasing carbon-forming tendency,oxidation rate, sludging rate, corrosion and the like.

The principal feature of the present invention is the use of a new classof organic acid compounds in lubricating oils. These materials are foundto be superior in aggregate of their properties to the general class oforganic esters. No reason is apparent for their superiority, and theinventors content themselves with noting the fact without explanationthereof.

The particular class of compounds to which the present invention relatesare compounds of furoic acid, or pyromucic as it is sometimes called,the formula being C4H3OCOOH. The acid itself is includedas well as thevarious alkylated or hydrogenated acids, but the esters of these acidsare preferable to the acids themselves.

Among the esters, the monohydric aliphatic alcoholic esters are thebest, such as methyl, ethyl, propyl, butyl, and amyl, but higher alcoholesters such as lauryl, cetyl, octadecyland oleyl are quite satisfactory.While the foregoing esters are most useful, it should be understood"that dihydric or polyhydric aliphatic esters may be used, such asglycol or glycerol esters and the esters of aromatic alcohols such asphenol, cresol and benzyl furoates.

The various compounds and particularly the esters are to be used inproportion of A; to 10% by weight of the oil, although usually 2% issufficient. Various other ingredients may be added, depending on theparticular use to which the oil is intended; for example, pourinhibitors, dyes, thickeners, soaps, oxidation inhibitors and the like.The esters are also suitable additions to gasoline and give it excellentupper cylinder lubricating properties.

The oil itself may be of a particular type, as for instance, derivedfrom a parailinic or naphthenic crude refined by the ordinary methods,such as acid or alkali treatment, solvent extraction, hydrogenation,destructive hydrogenation or the like.

While the furoic esters are of importance in liquid lubricants, they arealso important constituents for greases. Their function is not onlylimited to increasing the load bearing capacity,but also have a verydesirable plasticizing eflect on heavy high melting waxes which may benaturally present in the oil or may be added. These greases may be madein the usual manner with soda or potash, and the furoic ester ispreferably added after the grease is formed.

The effect of the furoic esters is particularly desirable in producingso-call reversible calcium greases Calcium greases, as made at thepresent time, contain small amounts of water which is essential to aproper grease consistency, and in consequence when the grease is melted,the ,water is lost and the grease structure is broken down, leaving ahard, solid, non-greasy mixture. Such greases are irreversible. Inmaking reversible lime greases, that is, greases which can be melted andresolidified without losing the grease structure, sulfonic compounds,especially the salts of mahogany sulfuric acids derived by the treatmentof mineral oils with concentrated or fuming sulfuric acid, must be addedto the grease, along with or in lieu of water, and a high melting wax,such as petrolatum, Montan, carnauba or candellia wax. Such compoundsmay be varied considerably in their properties of ranging the proportionof ingredients but they are very satisfactory, and are capable of beingmelted and re-melted without permanent loss of grease structure, whichis due to the combined action of the sulfonates, the wax and theplasticizing action of the furoic esters. The amount of wax may varyfrom say 5 to while'only small amounts of the sulphonates andfur0ates-say to 10% are necessaryusual1y 2 to 5% is best. It will beunderstood thatanothercalcium soap is present as well as lubricatingoil. Water may be present originally for to 1%, and glycerine, dependingon whether fats or fatty acids are used in making up the calcium soap.

The following examples are given to illustrate the method of producingthe above-described compositions and their properties:

The oil selected for the following tests was an S. A. E. 20 lubricatingoil, and to it was added 2% butyl furoate. One sample of the oil wasused as a blank for comparison with other samples which contained theaddition agent.

The following table shows the comparison of the oxidation rate z ExampleI Oxidation rate 200 C. cc./oxygen/10 cc. sample/15 minutes Hydrocarbonlubricating oil 62-93-56 Hydrocarbon oil plus 2% butyl furoate23-42-40-135 This action of the ester is remarkable in that the additionof most of the esters tends to increase the oxidation rate.

The oxidation rate of the oil was determined by passing oxygen in aclosed cycle at a constant rate, so as to bubble through a containerholding exactly 10 cc. of the sample. This was maintained at atemperature of 200 F., and at intervals of 15 minutes the amount ofoxygen absorbed was determined by measuring the remaining oxygen.

Example II The samples used in Example I were then tested for corrosionof bearings of several diiferent The foregoing tests were carried out ina strictlycomparable manner at a temperature of 210 F. and show that thebutyl furoate was substantially less corrosive than the oil itself inall three cases. The figures represent loss in milligrams.

Example III The samples used in the tests were then subjected to afurther test to show their oiliness characteristics on the Mougeymachine described by Mougey and Almen Petroleum News. The first testshowed a bear ing combination of aluminum and steel with hydrocarbon'oil as follows:

Lubricating oil Lbs/sq. in. Friction Hydrocarbon oil 18,000 ShearedHydrocarbon oil 2% butyl iuroate 25, 000 18 Hydrocarbon oil +-1% butylfuroate 25,000 38 Hydrocarbon oil butyl iuroate 25, 000 Sheared.

From the above it will be seen that the addition aof ester produced avery substantial increase in the oiliness and load bearing capacity ofthe oil. I

in the International Example IV As an example for the preparation of areversible grease, the following information may be of assistance:

About 69 by weight of a red machine oil having a viscosity of 300seconds Saybolt at 110 F. is placed in a fired kettle, and-ten parts ofhigh-melting petrolatum wax (180 F. melting point) is then added, andthe mass is heated to about 200 F. while thoroughly agitated. At thispoint'about fifteen parts of horse fat is addedture obtained by theusual methods employed in the preparation of lime soap greases. Thefinal material had the following compositions:

- Percent Red machine oil 69% Petrolatum wax, 180 F. melting point 10Lime soap 15 Calcium sulfonateu; 2 Butyl furoate 1 Water -l Glycerine 1The grease had a penetration of approximately 270 at 77 F., and onheating to 300 F. with loss of water was reduced to a thick fluid state.On cooling the product resolidifled into a smooth, uniform grease. TheA. S. T. M. penetration of the resolidified grease was 250-275 at 77 F.,and it was found that melting and remelting any number of times did notsubstantially change the quality of the grease.

For comparison, a grease made up in substantially the same way which didnot contain the butyl furoate showed a similar penetration of about 270before melting. After melting this dropped to about -125, showing thatthe material had become much harder and had'in fact lost its greaseproperties.

Example V To an aviation gasoline having an initial boiling point of F.and end point of 280 F. is added 1% of butyl furoate, which dissolvedreadily. The operation of the engine was smoother when this fuel wasused than when the fuel was used in the absence of the furoate.

The present composition and methods of manufacture are not limited toany theory of the function of any of the ingredients, nor to anyparticular ingredient which may have been used for illustrativepurposes, but only, to the followa ing claims, in which it is desired toclaim all novelty inherent in the invention.

3. Lubricatingoil according to claim 1 in which It was worked carefullyinto the com a neutral aliphatic monohydric alkyi ester of Iuroic acidisused. 4. An improved lubricant comprising a hydrocarbon lubricating oiland about to 10% ot a monohydric alkyi ester of pyromucic acid.

5. A solid lubricant comprising hydrocarbon lubricating oil, soap inproportion to solidifying the same, and a neutral ester of iuroic acid.

